Heavy duty relay
Discussion
My relay went today for the third time ..
It`s a mod for a higher output fuel pumps ,fitted it in the boot .. to maintain the voltage.
used the old fuel pump supply to power up the relay then fitted a heavy duty cable via a fuse from the battery through the relay to the fuel pump..
I wonder why they keep burning out ..!
Can i get a heavy duty one ,the original fuel pump relay in the footwell , ok no problems.
It`s a mod for a higher output fuel pumps ,fitted it in the boot .. to maintain the voltage.
used the old fuel pump supply to power up the relay then fitted a heavy duty cable via a fuse from the battery through the relay to the fuel pump..
I wonder why they keep burning out ..!
Can i get a heavy duty one ,the original fuel pump relay in the footwell , ok no problems.
What *EXACTLY* is burning out on them?
If it's the coil that's dying then that means that you need to start looking at that side of things (maybe the back EMF when the coil is energised and deenergised is frying the coils?) or is it the switched output (in which case maybe you need a higher power relay) but I doubt that as fuel pumps don't have that much draw?
Phil
If it's the coil that's dying then that means that you need to start looking at that side of things (maybe the back EMF when the coil is energised and deenergised is frying the coils?) or is it the switched output (in which case maybe you need a higher power relay) but I doubt that as fuel pumps don't have that much draw?
Phil
Bassfiend said:
What *EXACTLY* is burning out on them?
If it's the coil that's dying then that means that you need to start looking at that side of things (maybe the back EMF when the coil is energised and deenergised is frying the coils?) or is it the switched output (in which case maybe you need a higher power relay) but I doubt that as fuel pumps don't have that much draw?
Phil
I loose the feed to the pump,swop the relay in the boot and she starts up again ..(The relay will make a clicking noise but will not give a feed to the pump.If it's the coil that's dying then that means that you need to start looking at that side of things (maybe the back EMF when the coil is energised and deenergised is frying the coils?) or is it the switched output (in which case maybe you need a higher power relay) but I doubt that as fuel pumps don't have that much draw?
Phil
Don`t think there is as problem other than the relays eather being under sized or poor quality.
Edited by SILICONEKID340HP on Sunday 17th June 21:42
Edited by SILICONEKID340HP on Sunday 17th June 21:46
SILICONEKID340HP said:
Don`t think there is as problem other than the relays eather being under sized or poor quality.
I'm assuming you're using a 30 or 40 amp relay (that's the usual off the shelf size at somewhere like Maplin) and I'd doubt that your fuel pump is drawing more than that!Phil
Bassfiend said:
That's what I was thinking when I said it depends what's burning out but if the relay is still clicking then it doesn't sound like the coil is dying, no?
Phil
It may be that it is weakening the coil enough not to switch but enough to move and therefore click. I too can't see the fuel pump pulling 40A either. For the cost of a relay with a diode it is worth a try.Phil
SpecB said:
Bassfiend said:
That's what I was thinking when I said it depends what's burning out but if the relay is still clicking then it doesn't sound like the coil is dying, no?
Phil
It may be that it is weakening the coil enough not to switch but enough to move and therefore click. I too can't see the fuel pump pulling 40A either. For the cost of a relay with a diode it is worth a try.Phil
Phil
Bassfiend said:
SpecB said:
Bassfiend said:
That's what I was thinking when I said it depends what's burning out but if the relay is still clicking then it doesn't sound like the coil is dying, no?
Phil
It may be that it is weakening the coil enough not to switch but enough to move and therefore click. I too can't see the fuel pump pulling 40A either. For the cost of a relay with a diode it is worth a try.Phil
Phil
SILICONEKID340HP said:
What dies that mean in English . ?
http://www.halfords.com/webapp/wcs/stores/servlet/product_storeId_10001_catalogId_10151_productId_753349_langId_-1_categoryId_255229One of these. The voltage from the car can spike the relay and cause it to fail. The diode in the relay stops this happening.
SpecB said:
SILICONEKID340HP said:
What dies that mean in English . ?
http://www.halfords.com/webapp/wcs/stores/servlet/product_storeId_10001_catalogId_10151_productId_753349_langId_-1_categoryId_255229One of these. The voltage from the car can spike the relay and cause it to fail. The diode in the relay stops this happening.
Phil
Dont mess around with different relays. The diodes are there to prevent the switching electronics from being spiked and the twin pole units will need the correct wiring in the socket to make use of the extra live pin in the correct way. Get an old style capacitor used in the days of points, (mini- morris minor- MGB etc) and wire it across the pump- with the wire going to the +ve on the pump. This will remove the spike the pump creates as its powered off so reduce the arcing as the contacts open. This should reduce the burning to the contact faces. I dont see why a 30 AMP relay should have a problem switching the pump on, only the arcing as it switches off.
blitzracing said:
Dont mess around with different relays. The diodes are there to prevent the switching electronics from being spiked and the twin pole units will need the correct wiring in the socket to make use of the extra live pin in the correct way. Get an old style capacitor used in the days of points, (mini- morris minor- MGB etc) and wire it across the pump- with the wire going to the +ve on the pump. This will remove the spike the pump creates as its powered off so reduce the arcing as the contacts open. This should reduce the burning to the contact faces. I dont see why a 30 AMP relay should have a problem switching the pump on, only the arcing as it switches off.
Where do i get the 5 pin relay which are fitted in the footwell(there is two in the footwell). Why does it have an extra pin?In now useing two ,The original one in the footwell is being used for swithing for the second relay in the boot..
Daz, I was reading up on relays for a problem on someones Land Rover and found this document really useful
http://www.autoshop101.com/forms/hweb2.pdf
http://www.autoshop101.com/forms/hweb2.pdf
SILICONEKID340HP said:
Where do i get the 5 pin relay which are fitted in the footwell(there is two in the footwell). Why does it have an extra pin?
The one I linked to is 5 pin, i.e. a change over relay rather than on/off.Nice little article above, straight forward and clearly explained.
Just purchased these from Feabay
http://www.ebay.co.uk/itm/Boat-Car-Relay-with-diod...
They were for a mod for the higher output fuel pump fitted in the boot ..this one only uses 4 pins
The relays have 5 pins not 4 .
Can i use these for the 4 pin application .?
If not are they ok for a replacement for the two situated on the loom next to the battery.One for the fuel pump the other im not sure.
http://www.ebay.co.uk/itm/Boat-Car-Relay-with-diod...
They were for a mod for the higher output fuel pump fitted in the boot ..this one only uses 4 pins
The relays have 5 pins not 4 .
Can i use these for the 4 pin application .?
If not are they ok for a replacement for the two situated on the loom next to the battery.One for the fuel pump the other im not sure.
Edited by SILICONEKID340HP on Saturday 23 June 16:08
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